Novel magnetically separable Fe 3 O 4 @ZnO/AgCl nanocomposites with highly enhanced photocatalytic activities under visible-light irradiation

Preparation and Spectrochemical characterization of Ni-doped ZnS nanocomposite for effective removal of emerging contaminants and hydrogen Production: Reaction Kinetics, mechanistic insights

In this study, we report the successful synthesis of Ni-doped ZnS nanocomposite via a green route using ethanolic crude extract of Avena fatua. The as-synthesized nanocomposite was comprehensively characterized using Dynamic light scattering (DLS), Zeta potential, scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and Atomic force microscopy (AFM). These analyses provided detailed insights into the size, morphology, composition, surface properties, and structural characteristics of the nanocomposite. Subsequently, the synthesized nanocomposite was evaluated for their photocatalytic performance against the organic dye Methyl orange. Remarkably, the nanocomposite exhibited rapid and efficient degradation of Methyl orange, achieving 90 % degradation within only 30 min of irradiation under UV light. Moreover, the photocatalyst demonstrated an exceptional hydrogen production rate, reaching 167.73 µmolg-1h-1, which is approximately 4.5 times higher than that of its pristine counterparts. These findings highlight the significant potential of Ni-doped ZnS nanocomposite as highly efficient photocatalysts for wastewater treatment and hydrogen production applications.

Fabricating an adsorbent and micro-nano bubble catalyst through confining maghemite in the β cage of NaY zeolite

This work reports the ion exchange fabrication of maghemite (γ-Fe2O3) modified NaY zeolite (Fe2O3@Y) with bifunction of adsorption and catalysis. The Fe3+ successfully replaced the Na+ in the β cage of zeolite in the ion exchange process and coordinated with framework oxygens to form magnetic γ-Fe2O3. Therefore, most of the γ-Fe2O3 particles were confined in the β cages, which resulted in the high dispersal and stability of the catalyst. The Fe2O3@Y could remove methylene blue (MB) model pollutants up to 59.02 and 61.47% through the adsorption and catalysis process, respectively. The hydrogen bond between the OH- ions around the Fe2O3@Y surface and the N and O presented in the MB molecules enabled the chemical adsorption to MB, which accorded with the pseudo-second-order kinetic model. Further, the H+ existed in the solution and the β cage of zeolite promoted the collapse of micro-nano bubbles (MNBs). Then, the γ-Fe2O3 catalyst would be activated by high temperature and oxidated OH- to produce hydroxyl radicals for pollutant degradation. Thus, pollutant removal was attributed to the combined effects of adsorption and catalysis in the Fe2O3@Y + MNB system. In this work, the Fe2O3@Y was demonstrated as a potentially magnetic adsorbent or MNB catalyst for wastewater treatment.

Photo-Fenton assisted AgCl and P-doped g-C3N4 Z-scheme photocatalyst coupled with Fe3O4/H2O2 system for 2, 4-dimethylphenol degradation

In this study graphitic carbon nitride (g-C₃N₄ or GCN) and phosphorus doped graphitic carbon nitride (p-g-C₃N₄ or PCN) were prepared using facile thermal polycondensation method. Phosphorus doping was employed to preserve the non-metallic nature of GCN. The AgCl/PCN/Fe₃O₄ heterojunction was synthesized using a simple in-situ route. The photocatalytic performance of the GCN, PCN, Fe₃O₄ and AgCl/PCN/Fe₃O₄ was tested towards 2, 4-dimethylphenol (DMP) pollutant. The work explored improvement in physiochemical properties and reduction of band gap of GCN after P doping (through Tauc's plot method). Coupling with AgCl (silver halide) also enhanced photoinduced charge carriers' separation and migration ability due to apt band alignment among both AgCl and PCN photocatalysts which resulted in formation of direct Z-scheme charge transfer mechanism. Similarly, the incorporation of ferrimagnetic material i.e. Fe₃O₄ enhanced the generation of hydroxyl (^•OH) radicals via photo-Fenton process and facilitated photocatalysts easy separation from the aqueous medium. Through PL and EIS analysis the enhanced charge separation and migration ability in AgCl/PCN/Fe₃O₄ nanocomposite was validated. The attained DMP degradation efficiency of photo-Fenton assisted AgCl/PCN/Fe₃O₄/H₂O₂ Z-scheme nanocomposite was much higher i.e. 99% compared to other photocatalysts within 60 min of visible light irradiation following pseudo-first-order kinetics. Electron paramagnetic resonance (EPR) and scavenging tests confirmed the substantial role of ^•OH and ^•O₂^- radicals in the photo-Fenton reaction. Furthermore, liquid chromatography-mass spectrometry (LC-MS) analysis detected the generated oxidative products and mineralization pathways associated with DMP degradation. The proposed direct Z-scheme charge transfer route presented efficient charge separation and migration ability in AgCl/PCN/Fe₃O₄ nanocomposite. Recycle ability of the fabricated AgCl/PCN/Fe₃O₄ photocatalyst was tested up to 5 cycles with 90% removal efficacy, confirming the excellent reusability and stability of AgCl/PCN/Fe₃O₄ photocatalyst.

Mesoporous magnetic g-C3N4 nanocomposites for photocatalytic environmental remediation under visible light

Mesoporous magnetic Fe₃O₄/g-C₃N₄ nanocomposites were synthesized by a facile precipitation method using deionized water as solution. And the prepared magnetic materials were characterized by mean of various detection methods. At the same time, the photocatalytic activity of the synthetic material as photocatalyst under visible light was tested by taking the degradation of rhodamine B in water as a mark. Results show that as-synthesized Fe₃O₄/g-C₃N₄ nanocomposites have high specific surface areas of about 5-10.5 times that of pure g-C₃N₄ and high saturation magnetizations, which can ensure the smooth recovery of used nanomaterials under the action of external magnetic field. The addition of Fe₃O₄ greatly extents the response range of g-C₃N₄ nanomaterials to visible light and reduces the recombination rate of photoinduced electron-hole pairs. Meanwhile, the photocatalytic activity of the synthetic materials increases so that the degradation ratio of rhodamine B in water reached 97.6% after 4 h visible light irradiation. Furthermore, prepared magnetic Fe₃O₄/g-C₃N₄ nanocomposites have also excellent stability so that the degradation ratio of rhodamine B was almost not reduce after 5 times of continuous reuse of photocatalyst. Free radical scavenging experiments shows that hydroxyl groups are the main free radicals of photocatalytic reaction, peroxyradicals and holes play the secondary role. Therefore, it can be predicted that the synthesized mesoporous magnetic Fe₃O₄/g-C₃N₄ nanomaterials will have a broad application prospect in environmental remediation.

Crystal phase induced band gap energy enhancing the photo-catalytic properties of Zn–Fe2O4/Au NPs: experimental and theoretical studies

Au NPs on ZnFe₂O₄ enhances visible absorption, employed for paracetamol oxidation, where peaks were resolved by 2D HPLC.

Solar energy harvesting by magnetic-semiconductor nanoheterostructure in water treatment technology

Photocatalytic degradation of toxic organic pollutants in the wastewater using dispersed semiconductor nanophotocatalysts has a number of advantages such as high activity, cost effectiveness, and utilization of free solar energy. However, it is difficult to recover and recycle nanophotocatalysts since the fine dispersed nanoparticles are easily suspended in waters. Furthermore, a large amount of photocatalysts will lead to color contamination. Thus, it is necessary to prepare photocatalysts with easy separation for the reusable application. To take advantage of high photocatalysis activity and reusability, magnetic photocatalysts with separation function were utilized. In this review, the photocatalytic principle, structure, and application of the magnetic-semiconductor nanoheterostructure photocatalysts under solar light are evaluated. Graphical abstract ᅟ.

Preparation of ZnO Photocatalyst for the Efficient and Rapid Photocatalytic Degradation of Azo Dyes

Zinc oxide (ZnO) photocatalysts were synthesized by sol-gel method using zinc acetate as precursor for degradation of azo dyes under UV irradiation. The resultant samples were characterized by different techniques, such as XRD, SEM, and EDX. The influence of preparation conditions such as calcination temperature and composite ratio on the degradation of methyl orange (MO) was investigated. ZnO prepared with a composite ratio of 4:1 and calcination temperature of 400 °C exhibited 99.70% removal rate for MO. The effect of operation parameters on the degradation was also studied. Results showed that the removal rate of azo dyes increased with the increased dosage of catalyst and decreased initial concentration of azo dyes and the acidic condition is favorable for degradation. Furthermore, the kinetics and scavengers of the reactive species during the degradation were also investigated. It was found that the degradation of azo dyes fitted the first-order kinetics and superoxide ions were the main species. The proposed photocatalyst can efficiently and rapidly degrade azo dyes; thus, this economical and environment-friendly photocatalyst can be applied to the treatment of wastewater contaminated with synthetic dyes.

POLYVINYL BUTYRAL (PVB), VERSETILE TEMPLATE FOR DESIGNING NANOCOMPOSITE/COMPOSITE MATERIALS:A REVIEW

In current article, the versatile behaviour of Polyvinylbutyral (PVB)and its ability to form composite materials withvarious inorganic species is reported. PVB has hydrophilic vinyl alcohol groups and hydrophobic vinyl butyral groups. These groups behave as promoters of polymer adhesive and binders for organic moieties. The composite materials of PVB have been synthesized viaphysical as well as chemical both protocols. PVB is used as a constituent part in the formation of composite, induces a specific property in a resulting one which are utilized by various ways since it has stronger in binding ability, sharper optical clarity and able for providing flexibility and toughness in the formed composite. Varioussophisticated instrumentation techniques eg FTIR, XRD, FESEM, TEM etc. are reported for characterizations of samples. The composite materials have excellent film formation properties, and can be potential candidate for photoelectric as well as photovoltaic applications. The inorganic conducting species which do not have film formation ability can be useful by composite formation along with PVB. The green protocols for synthesis of composites may also useful for biological applications. 

Synthesis, characteristics and sonocatalytic activities of calcined γ-Fe2O3 and TiO2 nanotubes/γ-Fe2O3 magnetic catalysts in the degradation of Orange G

In this work, γ-Fe2O3 and TiO2 NTs/γ-Fe2O3 composites with good magnetism and sonocatalytic activity were prepared by a facile polyol method and utilize the principle of isoelectric point method, respectively. The structural and magnetic features of the prepared calcined γ-Fe2O3 and composite catalysts were investigated by transmission electron microscopy (TEM), powder X-ray diffraction (XRD), surface analysis, UV-Vis diffuse reflectance spectra (UV-Vis DRS), vibrating sample magnetometry (VSM) and zeta potential analysis. The effects of calcination temperature on γ-Fe2O3 phase variation, physical properties and sonocatalytic properties were investigated. The porosity, specific surface area, band gap energy and sonocatalytic activity of γ-Fe2O3 were gradually decreased with calcination temperature increased. TiO2 NTs/γ-Fe2O3 with appropriate composition and specific structural features possess synergetic effects such as efficient separation of charge carriers and hydroxyl radicals produced by heterogeneous fenton and fenton-like reactions. This enhanced the sonocatalytic activity for the degradation of Orange G under ultrasonic irradiation. The sonocatalytic reactions obeyed pseudo first-order kinetics. All these information provide insight into the design and development of high-efficiency catalyst for wastewater treatment.